"It is just unfair and unreasonable to expect two people to be doing the same job in the same workplace, working for the same employer, under different employment conditions."

The AMWU says Murray Goulburn’s commitment to three apprentices over the coming four years at its six processing sites is not enough.

"From our perspective, that is clearly not good enough," he said.

"We put a proposition that they should be picking up two apprentices per site over that period, which effectively means 12 across the state."

It is Murray Goulburn's view that this industrial action is unjustified

A Murray Goulburn spokesperson.

A spokesperson for Murray Goulburn said the co-operative was disappointed the unions had chosen to proceed with industrial action.

"It is MG’s view that this industrial action is unjustified," the spokesperson said.

"We have tabled an offer which we believe is a fair outcome for our employees, one which delivers wage increases above inflation, protects current entitlements and supports MG’s business to become more sustainable in the future."

The stop-work falls under the banner of protected industrial action and is not expected to last more than a few hours.

Murray Goulburn’s manufacturing operations are expected to continue as normal during the negotiation period.